US2550667A - Seal structure - Google Patents

Description

, May 1, 19 51 c. J. BLOM 2,550,667

SEAL STRUCTURE Original Filed Aug. 1, 1944 [VI/EN roe Patented May 1, 1951 SEAL STRUCTURE Carl J. Blom, San Marino, Calif., assignor to Byron Jackson (20., Vernon, Calif., a corpora- .tion of Delaware Original application August 1, 1944, Serial No. I547,617, now Patent No. 2,404,783, dated July v 30, 1946. Divided and this application June 11,

1946, Serial No. 675,984

This applicationis a division of my copending application Serial No. 547,617; filed August 1,

1944, now Patent No. 2,404,788, issued July 30 1946, for Submersible Motor.

This invention relates generally to seal structuresforeiiecting a fluid-tight seal between relativ'ely rotatable parts, and is directed particularly to improvements in sealing. devices of the type generally referred to as mechanical seals, wherein two walls of a chamber are sealed from the exterior. The seal for each wall comprises at least one pair of relatively rotatable sealing elements, usually in the form of plates or discs,

having cooperating surfaces disposed in a radial plane which interengage to effect a seal. The

stationary sealing element is mounted on afixed element, such as the wall of a housing or partition, in concentric relation to a shaft opening, and the rotating sealing element is mounted on a shaft or, other rotatable member.

It is customary to mount the rotating sealing element on the shaft for limited axial movement relative thereto and to provide means for yieldingly urging the rotatable sealing element toward the stationary sealing element, to force the seal-- the sealing faces, the stationary sealing element maybe forced away from its seat by fluid pres sure unless special provision is made for retaining it. Moreover, in the double sealing of two walls of a sealed chamber by these type seals, it

'is frequentIy preferred that one of the two seals admit exterior fluid into the chamber more'readily than the other, as is the case often in motor pump units wherein a sealed chamber exists having on its one side the dielectric fluid of the motor and on its other side the exterior pump fluid.

It is a principal object of this invention to provide a mechanical seal structure wherein one of two sealing structures for a chamber or other walled enclosure admits fluid into the chamber under a lesser pressure differential across said structure than does the other sealing structure.

A more specific object of this inventionv is to provide a double mechanical seal structure for a seal chamber for a motor pump shaft where said s Claims. (o1.2sc-11.15

7 seal chamber is interposed between the motor chamber itself and the pump exterior, wherein it is desired that dielectric fluid from the motor chamber pass into said seal chamber more readiiy than can the pump fluid pass into the said seal chamber. i 7

Yet another object of this invention is to provide a structure wherein the effective pressure areas of the particular seal which more readily admit exterior fluid cause fluid pressure to retain the stationary sealing element of such seal on its seat.

With the above and other objects in view as may appear hereinafter, reference is directed to the accompanying drawing, in which: 7

Fig. l is a View, partly in elevation and partly in longitudinal section, of a motorpump unit embodying the novel sealing device of this invention. 7

Fig. 2 is an enlarged fragmentary sectional View through line 2--2 of Fig. 1; and V Fig, 3 is an enlarged fragmentary sectional view through line 3-3 of Fig. 1.

Generally speaking, the instant invention comprises a double mechanical seal including two stationary sealing elements each mounted in one wall of a sealed chamber, and two rotatable sealing elements each mounted on the shaft passing through the sealed chamber and each cooperating with one of the stationary sealing elements to form two seal units, the elements of one of the sealing units providing relative pressure areas such that the fluid exteriorly of said seal unit is admitted more readily to the sealed chamber than is the fluid exteriorly of the other'seal unit. At the same time said relative pressure areas act to retain the stationary sealing element of the first seal unit against its seat.

In Fig. 1 there is shown a submersible motorpump unit as illustrative of a typical application of the novel mechanical seal device. An outer shell I is fitted at its lower end with a pump intake structure 2 and is connected at its upper end to a head structure 3. The head structure includes a reducer fitting 4 for connection to a casing or pipe C. The head structure also includes a motor head 5 located within the reducer fitting and adapted to suspend a motor case 6 within the outer shell I. The motor head 5 journals a shaft 1 by an upper bearing 8. Above the upper bearing the motor'head 5 forms an upper'protective fluid chamber 9 isolated fromthe reducer fitting or shell 4. The protective fluid may be any fluid having, primarily, dielectric properties sufficient to prevent shorting of the motor wind:

V silient rings 25.

into the shelf ii! so that the conductor may be brought into the oil chamber andthrough the motor head into the motor: case B. AAnoil line l3 which may be incorporated in the conductor cable or constitute a separate line, isprovided with a fitting for attachment to the shelf l8 so that the oil line communicates withtthe interior of the upper oil chamber 9.

A motor chamber id is provided within the motor case 6, and the elements of an'electric motor including the field coils l5 and the arma "ture- (not shown) arearranged therein.

An oil circulating pump 5 8 may be provided onthe-shaft i for the purpose of circulating cilin one direction through the 1 motor chamber, and in the opposite direction through oil jaclret fia incorporated in the motor case 6.

*The lowerend of the motor case'B is closed by a'seal'chamber housing ll which defines a seal chamber is. The shaft T extends through the seal chamber .and its protruding end is provided with a pump rotor 59 which draws fluid from the pump intake 2 and discharges it into a fluid pas 5 sage 29 formed between the seal chamberhousing ll, motor case 6, and outer shell i.

It is preferred to'arran'ge the pump rotor I9 :in such a manner that alow pressure chamber 19a is provided between the pump rotor and the under side of the seal chamber housing H.

A seal unit 2! is provided around the shaft 7 to isolate the seal chamber from the motor chambar. A similar seal'unit'22 is providedaround the shaft 7 to isolate the seal chamber-from the low pressure chamber 19a and-from the pumped The fixed seal rings 23 and 23a are preferably backed orseated on resilient rings'2-5 formed of rubber, synthetic rubben'leather or suitable material which are fitted'in the wall of the seal chamber. The rotating rings are backed by flex ible seal rings 26 of material-similar to' the re- The resilient rings'tfiand the seal rings 25 form thedouble function of first,

sealing the connections between the rings'23 and 23a and seal chamberwalls -and between'the rings 2 and 23aand the shaft 7 respectively;

and secondly, permittinglimited wobble adjustment of the rings -23 and 2 5 to effect perfect mating between their confronting sealing surfaces.

A spring 2'5 is interposed between theseal rings 26* to urge the rotating ringsi i and zl ia, against chamber if the external pressure is high enough to overcome'the force of the spring'fil and the pressure of the fluid in the seal chamber against the'rings 24.

It is desirable that the upper-seal unit Zl open atlxa'lesser pressure dilferentialthan the lower pressure.

one; furthermore, it is desirable that the fixed seal rings 23 and 23a have no special fastening means to hold them in place, but instead b held aaginst their respective resilient rings 25 by fluid Bothpf these objectives are accom- :,..,plished inethe arrangement shown inrFig. 2.

The fixed seal ring 2311 of the lower seal unit 22 is provided with a flange exposed to the seal .-chamber and which constitutes a pressure face than the lower end23 of the lower fixed seal ring 27a. The pressure face 21a is equal to or greater 2311; consequently, pressure in the seal chamber urges'this rin'g against its seat. The bore of the lowerfixed seal'ring'23a is substantially the same was. its mating rotating ring so that there is no appreciable. pressure area subject to pressure in .i-th eschamber l=3a and effective to raise the rotatingrring.

'One of the confronting sealing surfaces of the fixed'or rotating ring of the upper seal unit 2| is undercut adjacent the shaft '2. to'iorm confronting, pressure'faces' Zil; and? 28a. .-The effective area of these pressurefaces excee'd'sihe area .of the'upper end 39 of'the upper fixed seal ring 23 so that the pressure I- in "the motor-ohamber l-l urges theupper fixed seal ring 23 into its seat.

' Furthermore, the'pressure-in the motor chamber is effective against the pressure face 29a of the rotating ring to urge this ring downwardly against the spring 27.

Apressure' equalizing -bellows'3l is provided in the seal chamber [8. As shown best in Fig. '3,the bellows 3i comprises acircular head member or plate-32, and acircular footmember or disc 33 connected'by an annuiarly "corrugated bellows shellS l. The head *member 32 'is suitably securedto a wall of the seal-chamber housing, H preferably at the upper wall, by means of a hollow boltwhich extends through the upper-wall of the seal chamber housing into the motor chamber l l,'-so that-oil or other dielectric liquid from the motor chamber may-enter the bellows. The foot member 33 is provided with astem 35 which is'guided by a sleeve 3! depending from the head member" 32. -A spring 38 tends to-expand the bellows so that normally the bellows occupies an extended position as shown inFig. 3.

It will be apparent from theforegoing detailed description of one embodiment-of the invention that no mechanical retaining-means need be provided to hold the stationaryseal-ring 23 on its seat. The only surfacesonthis ring which are subjected to the pressure of the fluid in the motor chamber M and which constitute piston faces tending'to force'the ring in-one direction or the other are the oppositely facing surfaces 29 and 3G. Inasmuch as the surface--29 is'of greater area than the surface 38, the'net'efiect of ,the fluid :pressure acting'on thesesurfaces is a smallforce "':urging the ring toward its seat. This, relationship remains constant irrespective of the relative magnitude of the fluid ,pressuresin the motor compartment Maud in wtheseal compartment {8,

. respectively.

:sealing arrangements. it :will also lbe evident 'thatthednvention may be embodied in other forms than that shown,'withoutdeparting.from

the spirit'of theinvention or -the'scope of the appended claims.

I claim:

1. A double seal structure for sealing the junctures of a shaft with spaced Walls of a chamber through which said shaft extends comprising, in combination: first and second mechanical seal units each comprising a non-rotating seal ring and a rotating seal ring, the non-rotating seal ring of the first seal unit being adapted to be fixedly mounted adjacent the shaft opening in one of said walls in fluid-tight relation thereto, the non-rotating seal ring of the second seal unit being adapted to be fixedly mounted adjacent the shaft opening of the other of said walls in fluidtight relation thereto, the seal rings of each seal unit having mating sealing faces, said rotating seal rings being adapted to be slidably mounted on said shaft in fluid-tight relation thereto; and yieldable means urging each rotating seal ring into sealing engagement with its respective nonrota-ting seal. ring, the radially inner portion of the sealing face of the non-rotating seal ring of the first seal unit being undercut to prov as a radially extending pressure surface on the cooperating rotating seal ring exposed to the fluid ressure on outer side of the said one 1: 1, the effective pressure area of said pressure surface being greater than any pressure area the rotating seal ring of the second seal unit expesei to the fluid pressure on the outer side of said other wall, whereby the rotating seal ring of the first seal unit is movable out of sealing eneagement with its non-rotating seal ring respo sive to a lower pressure differential than is required to move the rotating seal ring of the second seal tion to the other of said walls adjacent the shaft opening therein; first and second rotating seal rings adapted to be slidably mounted on said shaft in fluid-tight relation thereto; and means yieldably urging said first and second rotating seal rings into sealing engagement with said first and second non-rotating seal rings, respectively, said first rotating seal ring having a pressure surface exposed to the fluid pressure on the outer side of said one wall, the effective pressure areaof said surface being greater than any pressure area on said second rotating seal ring exposed to the fluid pressure on the outer side of the other of said walls, whereby said first rotating seal ring is movable out of sealing engagement with said first non-rotating seal ring responsive to a lower pressure differential than is required to move said second rotating seal ring out of sealing engagement with said second non-rotating seal ring 3. A double seal structure for sealing the junctures of a shaft with spaced walls of a chamber through which said shaft extends comprising, in combination: a first non-rotating seal ring adapted to be fixedly mounted in fluid-tight relation to one of said walls adjacent the shaft opening therein; a second non-rotating seal adapted to be fixedly mounted in fluid-tight relation to the other of said walls adjacent the shaft opening therein; first and second rotating seal rings adapted to be slidably mounted on said shaft in fluid-tight relation thereto; and means ,Vieldably urging said first and second rotating seal rings into sealing engagement with said first and second non-rotating seal rings, respectively, said pairs of rotating and non-rotating seal rings having mating sealing faces, the radially inner portion of the sealing face of one of said first sealing rings being undercut to provide a pressure surface on said first rotating seal ring exposed to the fluid pressure on the outer side of said one wall, the effective pressure area of said surface being greater than any pressure area on said second rotating seal ring exposed to the fluid pressure on the outer side of the other of said walls, whereby said first rotating seal ring is movable out of sealing engagement with said first non-rotating seal ring responsive to a lower pressure differential than is required to move said second rotating seal ring out of sealing engagement with said second non-rotating seal ring.

CARL J. BDOM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 7 Date Re. 22,353 Karlberg July 27, 1943 2,200,413 Christman et a1. May 14, 1940 2,237,494 McCormack Apr. 8, 1941 2,365,046 Bottomley Dec. 12, 1944 2,395,705 Wool Feb. 26, 1946 2,418,194 Piccaido Apr. 1, 1947

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